Cam lapping machine



FebQZ, 1932. PLAYER ET AL 1,843,301

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Patented Feb. 2, 1932 warren stares earsar easies- SYDNEY PLAYER AND HERBERT S. INDGE, 0F WESTBORO, MASSACHUSETTS, ASSIGNORS TO NORTON COMPANY, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF IVLASSA- CHUSETTS CAM LAPPING MACHDYTE Application filed September as, 1929. Serial No. 395,935.

This invention relates to lapping machines, and particularly one which will serve to lap an irregular body, such as a cam, whose periphery is not concentric with its axis of rotation and which isnot of equal diameter throughout.

Heretofore, various lapping machines have been developed for producing an accurate and highly finished surface on a flat or cylindrical work piece which has previously been ground to approximately the required size. Such lapping machines and lapping methods as developed in the past have not been adapted in any way for lapping work of irregular contour, such as a cam, whose pee riphery is not isodiam-etrical' or concentric with the axis of rotation.

A camshaft used in automobile engines and the like'is required to revolve at very high speed and to move the engine valves with a fine degree of precision and in such an accurately timed relationship that the valves will open and shut at correct times relative to the timing of the spark and the compression of the gas. It is necessary that the cam be correctly shaped; hence, the. accuracy with which the surface has been finished-is of vital I importance. A rough surfaced cam is likely to wear the cam follower or to produce a noisy effect or otherwise act detrimentally. The automobile makers therefore appreciate that it is desirable to provide such a cam with a smooth surface and'one which is true in shape. These cams are ordinarily finished by a grinding operation but there are many problems involved in grinding such an irregularly shaped body, owing to its not having a surface concentric with its axis of rotation, and the grinding machines which forfn these cams are not able to produce a highly finished surface within a reasonable production time Consequently, the cams even after finish grinding have grain markings and rough chatter marks or other irregularities which make the cams'noisy and act inefficiently. This makes it desirable to finish the cam by a lapping operation.

It is accordingly the primary object of this invention to provide a machine which will surface of which is not concentric with its axis of rotation, and particularly to provide a machine which will lap such an article efficams arranged at intervals along the shaft and which have their rises and falls timed at different intervals, it is impossible to rotate the shaft so as to maintain a uniform surface speed between the cam and the lapping or abrading elements, but the shaft must be rotated at a substantially uniform angular In case of a camshaft which has a plurality of spaced speed. In this case, the lapping member tends to cut heavier on the rise of the cam as the cam is being rotated toward the lapping element and to cut lighter as the cam rotates and the lapping element follows down the fall on the cam. This means that a greater amountof lapping action is obtained on the rise than on the fall of the cam.

-' It is another-object of this invention to pro- I vide' a suitable mechanism to compensate for the difference in the abrading action on the rise and fall of the cam so that both the rise and the fall may be lapped a uniform amount.

It is a further object to provide a suitable driving mechanism for the camshaft so that it may be rotated first in one direction for a definite period and then reversed and rotated for an equal period in the opposite direction, whereby both the rise' and fall of the cam are lapped uniformly.

It is a further object of this invention to provide a suitable support and regulating mechanism for the lapping elements so that they may be maintained in yielding contact" with the periphery of the object being lapped at substantially a uniform pressure regardless of the contour of the object.

A further object is to providea suitable mechanism which permits both the'speed and the extent of reciprocation of the work to be varied relativeto the rate of work rotation, and thereby give the operator better control over the finish of the work.

A further object is to provide a method of lapping rotatable, non-isodiametric work, such as a cam, whereby the surface thereof will be finished to a desired degree of smoothness and particularly throughout all portions of itsperiphery.

\Vith these and other objects in view as will be apparent to one skilled in the art, this invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

In accordance with this invention, we have found that it is feasible to lap an irregularly shaped or non-isodiametric body, the surface of which is not cylindrical or concentric with its axis of rotation, such as a cam, by means of a lapping member which is pressed againstthe surface of the work during relative rotation of the two, and is held in operative contact therewith by means, independent of the work itself, which serves to provide" a desired lapping pressure. Also, the lap or the work maybe given a. motion longitudinally of the work axis which aids in or causes the lapping operation. The preferred form of lapping member is a rotatable body of suitable mate rial, such as an abrasive wheel of exceedingly fine grit size or a metal lap charged with abrasive or one used with loose abrasive powder. The lapping member is preferably mounted for free rotation, so that it may be driven by frictional contact with the positively rotated work piece. It may be held in operative contact with the work bymeans of a support which is arranged to move back and forth relative to the work axis asithe work revolves and to hold the lapping member in contact with the surface of the work. The

spring, which may be adjusted to give a proper degree of pressure between the lapping ele- If more than one cam is ments and the work. to be lapped, a series of independently arranged lapping elements are provided, each one being so spaced and arranged that it will contact with the proper cam on the work and will follow its contour as the cam rotates.

A special feature of this invention involves the provision of means for lapping the work while it rotates in one direction through a given cycle of operations and reversing the direction of rotation so as to lap the work in the opposite direction through an equal cycle. This serves to lap'both the rise and fall of the cam to the same extent, accomplished by means of a timing mechanism arranged to throw a clutch and stop the relative rotation between the work and the lapping member after a predetermined num- It is preferably ber of rotations. Then, by means of a reversmg mechanism, the work is rotated in the opposite direction for the same number of turns and the clutch is again thrown. The

speed and the extent of relative reciprocation between the work and the lap may also be varied so as to give the operator better control over the lapping action.

It will also be apparent frpm the following description, as well as the scope of the appended claims, that. a machine embodying various aspects of this invention is also applicable for lapping other types and shapes of -work, such as a cylindrical piece, which is rotated about its own center.

One embodiment of this invention hasbeen lapping machine having parts broken away to more clearly show the driving mechanism;

Fig. 3 is a right-hand end View of the machine, as shown in Fig. 2, with part of the upper frame broken away to more clearly show the arrangement of the lap supporting heads and operating parts.

Fig. 4 is a lefthand'end view of the machine, as shown in Fig. 2, having the headstock and part of the base broken away'to more clearly show the arrangement of the operating parts;

Fig. 5is a horizontal sectional view on an enlarged scale, on the line 55 of Fig. 2, to illustrate the operating parts of the work rotating and reciprocating mechanisms in the headstock;

Fig. 6 is a cross sectional view on a reduced scale, taken approximately on the line 6-6 of Fig. 5;

Fig. 7 is a cross sectional view on a reduced scale, taken approximately on the line 7-7 of Fig. 5;

Fig.8 is a fragmentary sectional view taken approximately on the line 8-8 of Fig. 5;

Fig. 9 is a horizontal sectional view through the footstock taken approximately on the line 9-9 of Fig. 2 showing the operating handle and associated parts in broken lines;

Fig. 10 is a fragmentary perspective view on an enlarged scale, showing the mechanisms for adjusting the length of reciprocation for the work spindle; and

Fig. 11 is a fragmentary perspective view on an enlarged scale showing the mechanism for simultaneously releasing the tension of the spring and weight upon the lapping members.

As shown in the drawings, a camshaft may be lapped by a machine in which the work is both rotatedand reciprocated, while each cam is independently lapped by means of a freely rotatable abrasive wheel held yieldingly but independently of the work, in operative. peripheral contact therewith. Such a camshaft lapping machine may comprise a lVor/v rotating and reciprocating mechanism A suitable headstock mechanism is provided so that the work piece 14 to be lapped may be rotated and reciprocated for a variable but predetermined time to produce the desired lapping action upon the work piece. The work piece is supported at one end by a rotatable sleeve 20 which is slidably mounted.

within the flange 22 projecting from the headstock 12. A spindle 23 is rotatably mounted in the bearing 24 at one end and bearings 25 at the other end and is arranged to transmit a rotary motion to the sleeve 20 by means of a pin 27 which is fixed relative to the sleeve 20 and passes through an elongated slot 28 within a disk-shaped projection 29 on the end of the spindle 23. A work driving pin or dog 30 is fixed to the pin 27 and passes through an aperture in the projection 29. The pin 3O engages a driving plate or dog 31 fixed to an end of the work and serves as a driving member to rotate-the work piece relative to the lapping members. The pin 27 is arranged so that it maybe retracted to telescope the sleeve 20 and the driving pin 30 within the flange 22 to permit placing a piece of work in the machine and then sliding the sleeve 20 and the driving pin 30 into operative relation with thework. The sleeve 20 and driving pin 30 are moved relative to the spindle 23 by means of a rod 32 which is slidably mounted within a central aperture in the spindle 23. The rod 32 is normally held in an operating position by a spring 33 which engages a shoulder within the spindle 23 and a shoulder on the rod 32. The movement of the rod 32 may be'controlled by any suitable mechanism, such as a manually operable lever 35 pivotally mounted in the front of the machine. This lever is connected to the forward end of a shaft 36 which has on its other end a projecting arm 37 adapted to engage the surface of a yoke 38 mounted to rock on a shaft 39. The yoke 38 engages an annular groove 40 in a sleeve 41 which is in turn connect-ed by a pin 42 with the reduced portion 43 of the rod 32. The pin 42-passes through an elongated slot 44 in the spindle 23 so that the movement of the yoked member 38 is transmitted through the sleeve 41 and pin 42 to move the pin 27, sleeve 20 and pin 30 endwise as desired.

To produce the desired lapping action, the work is reciproeated relative to the lapping members while they are relatively rotated. To permit the reciprocation of the spindle 23 andat the same time provide a driving connection with the work piece, it is necessary to provide a suitable yielding connection between the spindle 23 and the sleeve 41 so that the driving pin 30 will always be maintained in operative engagement with the work during reciprocation thereof. To accomplish this, a sleeve 45 is secured to a. re-

duced portion 46 of the spindle 23 and is protake the thrust of a spring 47 in one direction while an inwardly projecting flange on the sleeve 41 serves to engage the opposite end of the spring so that the tension of the spring is at all times maintained to hold the spindle 23 in a direction toward the right, as shown in Fig. 6, and thereby maintain the driving dog 30 and the sleeve 20 in proper driving and supporting contact with the work during the lapping operation while the work is being r0- tated and reciprocated.

The spindle 23 may be rotated by any suitable mechanlsm, such as a Worm gear 50, which is mounted on a sleeve 51 rotatably supported by the bearings 25. The sleeve 51 is slidably keyed to the reduced portion 46 of the spindle 23 by means of a key 53, so as to rotate the spindle 23 while it is being reciprocated. The worm gear 50 meshes with a worm 54 whichis keyed to a cross shaft 55. A motor 60, pivotally mounted in the base of the machine, is connected by a driving belt 61 to rotate a pulley 62 on the shaft 63. This shaft is connected by a suitable gear mechanism to rotate the shaft 55 and the spindle 23 at the de ired speed in either direction. As illustrated, in the drawings, the

shaft 63 is provided with a gear 64 which 'a sprocket 68 on the shaft 55 to rotatethe worm 54 and also the spindle 23 in the op- .posite direction. Either the gear 65 or the s )rocket 68 may be connected to rotate the shaft 55, in either direction, by engaging a clutch member 7 O'with the clutch teeth 71 on the gear .65 or the clutch teeth 7 2 on the sprocket 68. The clutch member 7 O is slid-v ably keyed t0 the shaft 55 and maybe shifted by any suitable mechanism, such as by means of a yoked member 7 5 having projecting pins 76 engaging an annular groove 77in the clutch member 70. The yoked member is mounted on a vertical shaft 79 which maybe rocked by a manually operable lever 80 to engage either set of driving members to rotate the spindle 23 in the desired direction. The

'vided with an outwardly extending flange to v be equalized.

clutch may be held in a neutral position by swinging the manual control lever 80 so that an arrow point 81 on an arm 82 will engage a correspondingly shaped recess 83 in a pivotally mounted lever 84. The lever 84 is held in engagement with arm 82 by means of a spring 85. A pair of springs 86 and 87 are connected to the arm 82 at their inner ends and to fixed studs 88 and 89 respectively at their other ends to tend to maintain the arm 82 in a neutral position so that the arrow point 81 is in engagement with the corresponding notch 83. I

For lapping various types of work, it is essential that a suitable timing mechanism be provided to control the extent and duration of the lapping operation so that each object to be lapped may be given a definite lapping action and the lapping operation will ,1 then be terminated automatically. In the lapping of cams and the like, due to the thrust of the lapping members as they roll in engagement with the surface of the cam, it is essential that the shaft be rotated first in one direction for a definite period and then shifted into a reverse direction so that the lapping action on the rise and fall of the cam will To accomplish this result suitable connections are provided so that the clutch may be automatically disengaged with a gear 99. The latter is provided with I an extending hub 100 which is rotatably 1 mounted in suitable bearings 101 in the frame 12 of the headstock. A manually operable lever 102 is mounted on the end of the frame 96 so that the frame 96 may be rocked to mesh either the gear 92 or the gear 97 with the gear 99 to produce either a fast or a slow speed of rotation of the gear 99.

An eccentric portion 103 is provided on the gear 99 which is engaged by a connecting rod 104. A pawl 105 is mounted ona stud 106 on the other end of the rod. The pawl 105 engages the teeth of a ratchet wheel 107 which is mounted on the end of a shaft 108.

A cam 109 is mounted on the shaft 108 and is engaged by a follower 110 keyed to a shaft 111. The shaft 1.11 is mounted in suitable bearings 112 in the headstock frame 12 and serves as a support to rock the lever 84. The cam '109 is so shaped that after a predetermined number of teeth on the ratchet wheel 107 have been picked by the pawl 105, a high portion of the cam 109 will rock the follower 80 towards the right, engage the clutch member 70 with the clutch teeth 71 and move the parts connected thereto into the position as 1 illustrated in Figs. 1 and 5. The rotation and reciprocation of the Work piece is then started and continues until the cam 109 rocks the follower 110 after a predetermined number of reciprocations of the rod 104, and so rocks the shaft 111 and moves the projection 83 so as to permit the arm 82 to swing to a neutral position and thereby disengage the clutch 70. The lever may then be moved towards the left to move the clutch member 70 into engagement with the clutch teeth 72, thereby engaging the sprocket 68 to rotate the shaft 55 to rotate the spindle 23 and the work in the opposite direction. Rotation in this direction continues until the cam 109 rocks the follower 110 and shaft 111 to shift the lever 84 so that the released tension of the spring 86 will move the arm 82 towards the right, as viewed in Figs. 1 and 5, so that the arrow point 81 engages the correspondingly shaped notch 83 thereby stopping rota tion' of the work in the reverse direction. lever 113 is mounted on the outer-end of the shaft 111 so that the operator may readily rock the lever 84 manually to release .the

arm 82 and permit the spring 86 to throw the clutch member 70 to a neutral position at any t me desired during the cycle of operation.

To permit varying the cycle of operation,

so that the period of lapping may be varied according to the desires of the operator, a

lapping operation. A manual control lever 116 is mounted on the outer end of the support 115 so that the operator may readily turn the shield 114 from the operating posi-,

tion in front of the machine. The lever. 116 is provided with a suitably graduated scale 117 and a fixed portion of the headstock 12 with an index point 118. The operator, by manipulation of this control, may turn the In the preferred construction, the work piece is given a combined rotary and reciprocating motion. To accomplish the reciprocation of the work, an eccentric pin 120 is held in fixed relation with the gear 99 during rotation thereof, and a connecting rod 121 in en-- gagement with the eccentric pin 120 at one end is connected at the other end to a projection 122 of a yoked member 123 which engages the pins 124 in the collar 125. The

collar 125'is rotatably mounted on a portion of the wheel spindle 23 and is held against rotation by engagement of the pins 124 with projections of the yoked member 123 while the spindle rotates. The parts are arranged so that reciprocation of the yoked member 123 is transmitted to reciprocate the spindle 23 and the work piece 14. When the spindle 23 is rotated during the lapping operation,

.the shaft 55, through the gear mechan sm,

rotates the gear 99 and revolves the eccentrio pin 120 to simultaneously reciprocate the spindle 23 and the work piece 14.

For certain types of work, it is desirable that the extent of reciprocating motion be adjustable so as to obtain the desired lapping action. To accomplish this, the pin 120 is mounted on an eccentric stud 127 which is journaled within a hole 128 in the sleeve 100.

The pin 120 is eccentric to the stud 127 andthe hole 128 is eccentric to the axis of rotation of the sleeve 100 so that by rotating the stud 127 relative to the sleeve 100, the eccentricity of the pin 120 may be varied to change the length of reciprocation of the work spindle 23. The stud 127 is provided with.

nuts 129 engaging a threaded portion 130 on the outer end of the stud 127 so that after .the adjustment of the eccentric pin 120, the stud 127 may be locked into rigid engagement with the sleeve 100 and the gear 99.

Footstoclc by a center 21 mounted on the outerend of a rotatable spindle 140 so that the spindle and center rotate freely as the shaft is rotated during the lapping operation. Due to the reciprocation of thework piece during the lapping operation, it is essential that the center 21 be maintained in contact with the end of the work piece with suflicient pressure to properly support the work during the reciprocation thereof. As illustrated in Fig. 9 of the drawings, a spring 141 surrounds the spindle supporting sleeve 142 and is arranged to exert a pressure sufficient to maintain the center 21 in operative engagement with the work. A

Lapping arms To produce the desired lapping action on the work piece, which has a plurality of spaced portions to be lapped, it is preferable to provide a plurality of lapping members arranged to simultaneously engage the various portions to be lapped so that the entire work piece may be lapped in one operation. The lapping members and the work piece are rotated relative to each other as well as reciprocated relatively to produce the desired lapping action. It is preferable that the lapping members he maintained in yielding contact with the work with sufficient pressure so as to producea substantially equal lapping action during the entire rotary engagement between the lapping members and the periphery of the work piece. As shown in the drawings, a mechanism has been illustrated which is particularly adapted for the lapping of camshafts in which the plurality of cams on the shaft are simultaneously lapped. The; 95

motor are designed with the cams spaced closely together on the shaft. It is consequently desirable to provide suitable supports for the lapping members so that they may be arranged to contact with the cams on the camshaft; To accomplish this alternate lapping arms 154 are mounted on supports 155 which are in turn supported on a shaft 156 journaled in the frame 16. By utilizing this construction it is possible to provide adequate support for the lapping arms so that they may be arranged to correspond with the closely spaced cams on the camshaft.

To increase the lapping action, it is preferable to provide a second set of laps mounted on lapping arms 158 and 159 which are pivotallyconnected to the supports 152 and 155 and shafts 153 and 156 respectively. Suitable laps 160 are mounted on the lower ends of the arms 150, 154, 158 and 159-and are arranged to engage the rear of the work. These laps may' be of any suitable construction, such as a rotatable lapping wheel which may be either freely rotatable on the studs 161 0': such as fixed lapping blocks as would be provided if the abrasive blocks were held non-rotatable. The laps may be either of metal charged with abrasivepowder, lapping elements to which loose abrasive compound is fed, or

preferably made of a-bonded abrasive strucas vitrified ceramic material or an organic bond of the phenolic resin type. As illustrated in the drawings, however, the lapping wheels 160 are freely rotatable on the supporting studs 161 and arranged so that they may be maintained in frictional rolling contact with the periphery of the work piece'being lapped.

Due to the irregular contour of the work plece, it is necessary that the lapping members be provided with suitable supports so that they may be held inyieldable contact with the work and move towards and from the work center as they follow the periphery of the irregularly shaped rotating work piece. It is desirable, also, that the lap be maintained in contact with the surface of the cams with a substantially uniform pressure at all times during the lapping operation. This may be accomplished by a mechanism comprising a link chain 165 connected to a link 166 projecting through a portion 167 of the la-ppng arm 150. The link 166 is threaded and provided with a nut 168 to permit adjustment of the link and chain 165 relative to the lapping arm. The other end 0f the chain 165 is connected by a link 169 to the short arm 170 of the bell crank lever 171. The bell crank lever 171 is mounted to rock on a shaft 172 mounted in the frame 16. The other arm 173 of the bell crank lever 171\is connected to one end of a spring 174,

- the other end of which is connected to a pivotally mounted lever 175 which is pivoted to a supporting shaft 17 6 journaled in the frame 16. The other end of each lever 17 5 is provided with a suitable weight 177 of suflicient size to maintain the desired tension 'on each spring 174. All of the arms 150 v idler pulleys 180 and are connected by arms 181 on a set of bell crank levers 182. To permit adjustment of the chains 17 8 relative to the lapping arms 158 and 159, a suitable mechanism may be provided, such as adjustable brackets 183 which support the idler pulleys 180. Thebrackets 183 are mounted on the supporting members 152 and 155 and are adjusted by means of screws 184 which are connected so as to adjust the brackets 183 relative to the supporting members 152 and 155. The bell crank levers 171 and 182 are in turn connected to springs 174 and levers 175 which are supported and arranged as above described. It will be readily apparent from this disclosure that the weights 177 acting through the springs 174 will provide suitable tension on the chains 165 and 178 and maintain the laps 160 in yielding contact with the surface of the cam being lapped at a substantially uniform pressure during the lapping operaton. Each of the lapping arms 150, 154, 158 and 159 is provided with independent spring and weight mechanisms so that each lapping wheel is held independently in yielding contact with the work. The supports 152 and 155 are provided with suitable clamping screws 190 so that they may be adjusted longitudinally of the supporting shafts 153 and 156 and then locked rigidly relative to the shaft.

In accordance with this invention, mechanism has been provided so that when the lapping operation on a camshaft has been completed the yieldable pressure on all of the lapping wheels may be simultaneously released so that the operator may readily remove the finished piece of work and replace it by a new piece. To accomplish this, the machine is so arranged that all of the weights may be raised to release the tension on the springs 174. As shown, the shaft 17 6, which supports the levers 175, is provided with a key 192 which extends the entire length of the shaft 176. Each of the levers 175 has a keyway 193 of sufficient width to permit a limited rotary motion of the shaft 176 without disturbing the position of the levers 175.

In order that the levers 17 5 and weights 177 i may be simultaneously raised to release the tension of the springs 174 and consequently relieve the pressure of-the lapping wheels on the work, a suitable mechanism is pro vided to rock the shaft 176. This may comprise a handwheel 195 which is mounted on the front end of the shaft 196 carried in a bearing 197 on the base 11. The rear end of the shaft 196 is provided with a threaded portion 198 engaging a nut 199 fixed to the base 11. The end of the shaft 196 is ar ranged to engage an arm 200 which is rigidly keyed to the shaft 17 6. It will be readily" apparent from this construction that when the operator turns the hand wheel 195 rotary motion of the screw 198 relative to the nut- 199 moves the end of the screw relative to the arm 200. When this screw is moved n a direction towards the right, as viewed in Figs. 4 and 11, the shaft 17 6 Wlll be rocked relative to the levers 17 5 until the key 192 ,engages the opposite end face 201- of the enparent from the foregoing disclosure. The operator places a camshaft or other suitable work piece in the machine inalignment with the work supporting sleeve 20 and driving pin 30 at one end and the footstock center 21 at the other end. He then swings the lever 143 to bring the footstock center 21 into engage-' ment with the work. Swinging the lever 35 moves the work supporting sleeve 20 and driving pin 30 into driving and supporting engagement with the other end of the work piece. The lapping operation may then be started by moving the lever 80 towards the right, as viewed in Fig. 1, to engage the clutch member 70 with the clutch teeth 71 connected with the gear 65 to rotate the shaft 55 and the spindle 23 and work piece 14 in one direction. This rotation continues until the cam 109 raises the follower 110 and rocks the shaft 111 and arm 84 and permits the released tension of the spring 87 to throw the clutch into a neutral position and stop the lapping operation in that direction. The operator then. shifts the lever 80 towards the left (Figs. 1 and 2) so that the clutch member engages the clutch teeth 72 and locks the gear 68 into driving engagement to rotate the shaft 55, the spindle 23, and the work piece 14 in the opposite direction. This rotation in the opposite direction continues for a similar period until the cam 109 rocks the follower 110 and shaft 111'to swing the arm 84 so that the re leased tension of the spring 86 will swing the arm 82 towards the left, as viewed in Fig 1, to move the clutch member 70 into a neutral position. During this rotation of the shaft in each direction the reciprocating mechanism operated by the gear 99 produces an work and the lap, one relative to the other, for the lap which acts independently of the axial reciprocation of the work piece. The equal cycles of rotating in each direction insure an equal lapping action on the rise and fall of the cam, thereby eliminating any tendency of one lapping element to run away from the surface while rolling up the rise or when rolling down the fall of the cam.

Having thus described the invention, what is claimed as new and desired to secure by Letters Patent is:

1. A machine for lapping rotatable nonisodiametric work, comprising means to support the work, a lap frictionally engaging the. periphery of the work, means to rotate the work and the lap about the work axis, one relative to the other, and thereby cause a lap-' ping action, and means acting independently of the work to maintain said lap with a posi-' tive but substantially uniform pressure against said non-isodiametric work throughout the entire lapping operation.

2. A machine for lapping rotatable nonisodiametric work, comprising a work support, a lap, a support for said lap arranged to maintain it in frictional contact with the work, means to rotate and reciprocate the and thereby cause a lapping action, and

means independent of the work to hold thev the lap about the work axis, and thereby causing the lap to drag against and lap the work, means whereby the lap may move towards and from the axis of the part being lapped and maintain contact with the non-isodiamet-.

ric work surface during such relative move- .ment, and means for relatively reciprocating the lap and the work to provide a break-up motion in the lapping operation.

4. A lapping machine for lapping rotatable non-isodiametric work, comprising a support for the work, means to rotate and reciprocate said work, and two independently movable laps arranged to frictionally engage opposite sides of the non-isodiametrio work and move towards and from the axis of the part being lapped as the latter is rotated and reciprocated.

5. A lapping machine for rotatable nonisodiametric work comprisinga work support, a lapping element, means to rotate and reciprocate said work and lapping element, one relative to the other, and with respect to the work axis, means independent of the work to maintain said lapping element in operative contact with one side of the non-isodiametric work with a predetermined but uniform pressure, and means for adjusting said pressure. I

6. A machine for lapping non-isodiametric work comprising a work support, a lap frictionally engaging the work periphery as the parts are relatively rotated, rotative means for relatively moving the work surface and the lap about the work axis, and therebyv causing the lap to drag against and lap the work, means whereby the lap may move towards and from the axis of the part being lapped and maintain contact with the nonisodiametric work surface during such relative movement, means for relatively reciprocating the lap and the work to provide a break-up motion in the lapping operation, and means for holding the lap against the work surface with a substantially uniform pressure for all positions of the WJI'k.

.7. A lapping machine for rotatable nonisodiametric work comprising a support for the work, a freely rotatable lap peripherally engaging the work, means to rotate the work and lap relatively about the work axis, means to reciprocate the work and the lap relatively parallel with the work axis, and a support ingly impressing'a desired uniform g able non-isodiametric work,

predetermined lapping period.

work to hold the lapin operative engage ment with the non-isodiametric work during the lapping operation.

8. A lapping machine for rotatable, nonisodiametric work comprising means to support and rotate a work piece, a freely rotatable lap, means independent of the work to hold-the periphery of the lap in operative engagement with the periphery of the work, means to reciprocate said work and lap, one relativeto the other, and means for yieldpressure 1 upon the work by the lap.

9. A machine for lapping rotatable non-- isodiametric work, comprising means to rotate andreciprocate the work upon its axis, freely rotatable laps engaging opposite sides of the work which are independently movable toward and from the center of Work rotation, and independent means to impose a .about its axis, and clutch mechanism for reversing the direction of rotation of the work. 11. A lapping machine for rotatable Work, comprising a support for the work piece,

means to reciprocate'said work axially, a

lap, means to maintain said lap in operative contactwith the periphery of said Work,

- means to rotate said work in either direction driving mechanism to rotate the work in either direction relative to the lap and about the work axis, and automatic mechanism act:

ing in timed relation with the driving mechanism to stop the work rotation after a r0tatcomprising means to support and rotate the work upon its axis, lapping members on. each side of the work movable independently towards- 13. A lapping machine for lapping and from the center of work rotation, means to: maintain substantially uniform pressures of the laps against the periphery of the work piece during its rotation,'and means acting in timed relation with the work rotation to stop the lapping operation upon completion of a predetermined cycle of the work rotapendent laps operatively contacting with said portions of the surface of the work, means to hold each lap against the work under a definite uniform pressure during the lapping operation, and means to release the pressure of all the laps simultaneously.

15. The method of lapping a camshaft having a plurality of spaced cams of nonisodiametric shape comprising the steps of rotating the camshaft first in one direction 

